On Dec 18, 1:25 pm, Puddin' Man wrote:
Thanks for previous help. Yeah, it's a learning experience: my expertise
is miniscule.

The EKB is Yamaha PSR-12, about 20 years old. I can leave it powered
for a long time, no problem. Play it for 30-90 seconds and it
freezes up, keys don't work.

It has 4 boards:

1.) "1684 PN1" - large board with markings for voicings
2.) "1684 PN2" - large board with markings for effects, etc
3.) Power Supply - from batteries or converter
4.) Switch - main power switch and master volume

I'm just trying to get a feel for what functions are implemented
on what boards ...

The headphone jack/speaker connects to 3.) via 3-element black wire.

1.) connects to 4.) via 2-element black wire.

4.) connects to 3.) via 8-element ribbon cable.
The 8 elements are as follows:

Label Color
----- ---------------------------
E white/pink stripe
5v white/gray stripe
B white/yellow stripe
T white/blue stripe
M white/pink marking
S white
E bare metal
E red

I get the feeling I stand no chance of trouble-shooting this unit
unless I can grasp the functions of this 8-element ribbon cable
(on *some* level).

Anybody got a feel for how the E B T M S E are coded?

I pulled 1.), cleaned and inspected, replaced it. No hep'.

Thanks,
Puddin'

"Well, there's two trains runnin'.
Ain't neither one goin' my way.
One run at midnight,
the other run just before day."
- from "Still A Fool", Muddy Waters, maybe 1949

I'd check the supply voltage(s), look for cracked solder, maybe flex
the board to see if theres any intermittant connections. Other than
that there's not likely anything you can do with it since its probably
full of custom ic's. Not worth the trouble if you ask me.....unless
its a Moog, Arp, Sequential, etc.